Cornelia Parker had a dramatic conversion. She was invited to an environmental conference at Oxford University and, tempted by the prospect of meeting such famous participants as Philip Pullman, she went. “My reasons were rather shallow,” Parker admits, but the event changed her life. “It was a complete wake-up call. For the first time I realised how terrifying climate change was. I could talk about nothing else. My poor husband... my poor friends... I was bombarding them with articles. I was reading voraciously... about anything: American foreign policy, oil production, food production.”

Clearly the environmental message resonated with Parker - even if it had never been given a political voice. She has always been close to nature, she says. The strong, tomboyish daughter of smallholder parents, she was brought up in Gloucestershire, milking cows, scything corn, feeding pigs and chopping wood.

Her artistic interests may subsequently have led her a long way from her rural roots (she now lives in the East End of London) but, with the unexpected arrival of a baby daughter, Lily, six years ago, when Parker was 45, she instinctively started retuning her sensibilities. “You just go on not worrying about the next generation until you have a child,” she says.

But, looking back, perhaps the signs were already in place. The photographs from her marriage in 1998 to the American artist Geoff Macmillan, for instance, were taken on Brooklyn Bridge, and there in the background are the twin towers, “us and the World Trade Centre... an emblem of our undying love,” Parker laughs. Then, three weeks after Lily was born, came 9/11, “and there I was nursing this tiny, precious baby while watching scenes of total destruction on the news”.

So how was she going to incorporate this new awareness into her art? In a sense it was already there. Parker is probably best known for her Cold Dark Matter, which suspends the myriad charred fragments of a blown-up shed on to hundreds of threads. A split-second moment of explosion is trapped in the piece. She made it in 1991, but it was only one of many works in which objects have been subjected to cartoon-like processes of destruction: crushed under steamrollers, peppered with bullets, struck by lightening, burnt by meteorites, dropped off cliffs.

Parker has always had an apocalyptic vision. “I suppose I have always been alert to the fragility of the world, and I have always been interested in addressing our fears of destruction,” she says. “I used to be pretty obsessed about the planet being obliterated by a meteor until global warming came along.

“I have never wanted my work to be didactic, to be annexed to a particular cause,” she says. “But when I look at old stuff I've made, I can see why people have so often seen political meanings”.

The shed, which was blown up by the Army, was associated with the IRA bombings that were happening about that time. But perhaps one of her most prescient pieces was made in 2004 from wood collected from a forest fire in Florida. It was started deliberately by the Forestry Commission as part of a woodland management programme, presumably. But then the wind caught it and it raged out of control, consuming thousands upon thousands of acres. “I didn't mean it to have any overtly political message,” Parker says, “but looking back it seems like a symbol of American politics.”

A year after she had been to the environmental seminar, she was invited to a biennale in the United Arab Emirates. The theme was “art, the environment and the power of change”. And Parker could hardly miss the irony. This was “the most consumerist, most decadent oilproducing nation in the world.”

At first she thought of showing her forest fire piece. But then she decided she wanted to be more direct. She decided to invite the outspoken, left-wing intellectual Noam Chomsky to come to lecture at the biennale. “This is the man who speaks about ‘apocalypse now'.”

When Chomsky couldn't come, she compromised and asked for an interview. “I wanted to do something very minimal: to include just him. And I wanted it to be as open to interpretation as possible, so I took all my questions out and just left his answers.” This is the film that she now presents at the Whitechapel.

It is called Chomskian Abstract, and it consists, quite simply, of footage of Chomsky talking about current affairs. His jersey is scruffy. His hair is grey. His delivery is calm. His words are measured and thoughtful and his opinions are clear and completely uncompromising.

Parker wanted to create a portrait of Chomsky. She has certainly experimented with contemporary alternatives to traditional portraiture in the past. In a 1995 collaboration with Tilda Swinton, for instance, she displayed the sleeping actress in a glass case and, in a project at the Brontë Parsonage museum, she tried to create a psychological portrait of Jane Eyre's author by photographing all the tiny alterations that the writer made to her manuscript. She also filmed an interview with a 90-year-old woman who claimed to be Branwell Brontë's great-grandchild. “I needed to capture her story before she died,” Parker says.

Something of this urgency lay behind her desire to create a portrait of Chomsky, now in his eighties. The problem with the finished piece, however, is that it is not visually interesting. Nor does it have any of the pleasing wit of Parker's conceptual pieces. All signs of artistry have been wilfully eradicated. It is all but indistinguishable from a piece of political propaganda. It is potentially as boring and, presented by any lesser artist, would feel pretentious to boot.

But Parker has a consistently probing talent. She has earned the right to our attention. And that is why it is worth pausing and giving her the benefit of the doubt.

Chomskian Abstract is not a great work of art. But it may turn out to be important. Parker is obviously struggling to find a way to embrace her new passion. With hindsight we will probably see this piece simply as a stepping stone on the way to somewhere more interesting. But still the work has a present point in that it expresses dissatisfaction with what art can achieve. Its dullness gives art's failures a visual form.

“I have always admired artists with a political agenda,” she says, “Joseph Beuys, for example, or Bruce Nauman. But I feel very hopeless about making something which has the power to change the way things are, like a politician or an activist can do. Art is a bit slow.”

But it can have another type of strength. “Art is always about reappraising the way we look at the world,” Parker says. “It can speak more eloquently than propaganda because it can inject emotion into facts. And sometimes it can work like a Stealth Bomber: it can slip under the radar and hit home.”

All Parker knows, she says, is that “if you make one great work of art in your life then your life has been worth living”. Chomskian Abstract is not this piece. But it could be the work that leads Parker there.

Chomskian Abstract will be showing at the Whitechapel from Feb 13 and will be part of a Friends of the Earth Forum on March 29

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